VAP

<center><img src="http://pictureposter.audiworld.com/711/vacuumstuff.jpg"></center><p>
I have my annual physical, bi-annual teeth cleaning, haircut and if I have time I'd like to get to my industrial parts supplier for s'more fittings and such.

But I'll leave you guys with a pic. See if you can figure out what it's going to be.

Cylindrical rod on left was the last part I worked on this morning and will be the first thing I get back to when I start in again. It's finished length will be exactly the same as the smaller part on right in pic but it's diameter while remaining a hex will be .250" larger diameter and its hex "points" will be radiused. I have to make it longer than necessary initially to allow me to hold on to it in either the lathe or the CNC as once I've done the 1/4" NPT threads on the opposite end I can no longer grab it there to work on. And cutting taper threads is fidgety bidness at best so far better I "start" there rather than finish there and screw the entire part up doing that aspect.

This piece will be nearly identical to the smaller piece on right. I got half-way thru the small piece and realized that 1/8" NPT would have insufficient flow and re-fill rates. But by making my own 1/4" NPT fittings allows me to bore them .100" larger ID than I can buy the fittings. This allows me to have closer to 3/8" NPT flow than "stock" 1/4" NPT fittings allow but retain the smaller sizes of the 1/4" fittings. I'm only able to bore over-size due to the use of FAR stronger 7075 aluminum ("poor man's titanium") as 6061 aluminum (small hex part in pic) would likely break in-use if not treated VERY gently.

This part has nothing to do with the distribution block or manifold. It will be used on the inlet side of Bertha and not the outlet side. It will have an o-ring groove machined into the base at bottom of 1/4" NPT threads and that's why there's a small ungrooved "flat" on the threaded stem between threads and base. It will have a single inlet which is the threaded
stem you see in the pic but it will have dual 3/8" barb outlets when finished.

The question is: where will it be threaded into and what components will it's two outlets serve?

Winner gets the one on right in picture ;-)

audiPete

Vacuum Gauge?

Jretal

that allows vac gauge to thread into it?

otherwise no clue :-P

Lago Blue

<center><img src="http://www.cranecams.com/include/showImage.php?type=heading&amp;id=39"></center><p>
...the Brake Booster separately?. Reason being, they are going to be your two biggest vacuum customers. The Brake Booster won't care, it will draw from either: the I/M or the Accumulator, whichever has the higher vacuum.

Zero leaks and the check valves will mean no waiting for "boost" (waiting for Bertha to "empty"). Max vacuum is available for start-up and continously thereafter. Better brake pedal feel, engine on or off.

However, could the original I/M to Brake Booster line be retained with check-valves (unlike the set-up in the link below) to allow the Booster to use engine vac. direct; -if- the Accumulator (and/or the other services it feeds) should leak?

All the remaining services can be fed from your smaller I.D. Distribution Block. This way, the VFPR and the I/M C/O can always get the benifit of full max. trapped vacuum, those remainimg will be metered as to specific needs to reduce unnecessary vacuum loss.

Mance, can the entire vacuum distribution be fed from Bertha's thicker (and thicken-able) end cap(s); and the thinner accumulator body wall be ignored?<ul><li><a href="http://www.cranecams.com/pdf/99590.pdf">Instructions For (the above pictured) Vacuum Reserve System...</a></li></ul>

odelay12v

i dont think so but had to atleast participate

quattro90S6

that will result as your "hub". Put a barb in each face of the hex, thus six barbs, and have them going to where ever vacume is needed. Its a distributor of vaccume, instead of the leaky plastic and metal fittings you had before, put this on the thicker stronger end

VAP

First it puts a MUCH larger diameter source of vacuum much nearer Bertha than pulling vacuum out of the small vac nipple at rear of IM on passenger side. Second it eliminates a vac line running from right rear to left front of engine bay. Vacuum build-up in Bertha is over 5 times faster with a shorter, larger diameter vacuum hose. To fill Bertha when completely empty from the rear IM vac nipple to 20 InHg takes 33 seconds after engine has started. To attain 20InHg in Bertha from the large front IM hose takes a hair over 5 seconds.

I will at least initially keep brake boost and Bertha on separate circuits "after" their individual check-valves. They will share a common circuit only up to their individual check-valves. Reason being it gives me 2 separate vacuum storage accumulators which increases my vacuum capacity and prevents catastrophic loss of vacuum to ALL vacuum-driven components in that event. Another reason is at this time, age and mileage I don't trust my brake vac booster system to be 100% leak-free. I've yet to test a 100k miles Audi vac diaphram that is TOTALLY leak free. I did smoke test the vac diaphram 2 years back when installing the UrS4 master cylinder and was getting trace amounts of smoke from the firewall master cylinder mounting flange through the hole in firewall where the MC actuator rod goes thru it and attaches to the brake pedal. I'll definately check for vacuum booster leak-down again some time during this project.

No sooner did I have the upper/lower caps installed on Bertha when it dawned on me I could've made my own upper sealing cap out of aluminum with a machined "flat" for better, more sealable inlet/outlet vacuum service lines. The one thing I want to avoid however is having a tangled mess of component vac service lines coming off of Bertha and going everywhere under hood. It would be messy at best and vacuum, like positive pressure diminishes with length unless larger diameter lines are used. So I'm going with the plan listed below:

1. Single 3/8" ID line from IM to Bertha.

2. Single 3/8" ID line from Bertha to distribution block.

3. 3mm lines from distribution block to solenoids and fuel pressure regulator.

If I can figure out how to wire things electrically I'd also like to run cruise controll off Bertha's vacuum and if that pans out later adapt door lock/unlock to also be part of total car "single-source" vac system and eliminate ALL vacuum pumps and related components.

Lago Blue

<center><img src="http://i196.photobucket.com/albums/aa144/axe_360/vacroute.jpg"></center><p>... and wondering (since "for every acceleration there is a corresponding de-accel...") if we might be well served to simply dedicate it's existing nearby original vacuum supply port (right/rear top of I/M) to the FPR; <i>alone</i>.

One advantage I see to your plan is that you can remove the other vacuum draws from the above location.

In this fashion it would still have a very short connection, and being acted on alone, a most rapid response to the throttle-plates's action.

Mind you, alternatively, it would also be neat to be able to adjust the fuel pressure down, while enroute (say, co-incident with engaging the cruise-control) by feeding it higher vacuum! An EGR F/V Solenoid type valve (complete with Adjustable Vacuum Regulator and Restrictor) might just be able to do that.

VAP

The one thing I've found with higher vacuum to the FPR is that it leans out the fuel at idle dramatically. Under 20 InHg and down to 15 InHg is what the FPR would prefer with stock ECU. I believe much of my recent emission test's HUGELY cleaner tailpipe samplings are the direct result of leaner fuel at idle as the result of dramatically higher vacuum at idle. In fact as much as the 12V likes to run with its idle fuel trim set to "fat-as-a-pig" standards I wouldn't be a bit surprised to find the stock ECU triggers a CEL related to "fuel trim level low" when the car idles with at/near 20+ InHg manifold vacuum at least initially, until the ECU adapts. At 22-24 InHg the ECU "may" not even be able to adapt. However, emissions-wise the tailpipe samplings become exponentially cleaner and there seems to be no drawback to idle smoothness whatsoever nor is there any risk, either real or perceived with "lean &amp; clean" idle A/F ratios. The less fuel the car gets at idle the happier everyone, including the engine is!

However, all this leanness at idle can and will reach a point of diminishing return at or near 24-25 InHg. The idle can start to get rought/erratic. My personal feeling is there's still plenty of fuel available to sustain smooth idle but that the injectors cannot make a finely atomized "mist" of fuel at SUCH a lower idle fuel pressure which is now approaching half of the pressure the injectors are accustomed to working with and they start to dribble/drip instead of making a good conmbustible finely atomized mist. I believe I'm faring better in this regard due to my use of smaller-than-stock injectors that are balanced/blueprinted. A smaller BSFC injector is capable of generating a finer mist of fuel at lower fuel pressure than a larger injector.

Therefore when the dust settles and I'm done with this project my FPR vacuum supply really needs to come from the IM which while it has MUCH higher vacuum than I started with it still "makes" less than is stored within Bertha at any given time.

Lago Blue

... and the FPR's response to closed throttle would be more positive engine braking thereafter, even before you use the new and improved brake pedal response.

Very interesting info about the FPR's response to vacuum and it's preferred range, thanks.

Perhaps on a stock engine, one might be able to step down below even what BSFCs both you and 4audiQ chose for injector capacity to gain improved (high vac./low fuel pressure) fuel spray pattern without running out of gas at the top end?

RC's signature injectors are looking more economical all the time!